This invention relates to a keyboard device which is suitable for use in an electronic musical instrument.
Generally speaking, a keyboard mechanism for a musical instrument is required to be constructed such that when the key is initially depressed, the key gives a relatively heavy touch sensation to the performer, and the touch sensation decreases in the succeeding stage of key depression, and that a damper effect which manifests various musical shading can be provided so that the performer will not be tired even after a long performance. For example, in the performance of a music with a fast tempo, the mass of the key should be small, whereas for music of slow tempo, the mass of the key should be large to increase a touch sensation. One example of the keyboard devices that satisfy these requirements is the keyboard device of a grand piano.
A keyboard device of a piano is constructed such that the conventional action mechanism strikes a string when driven by a capstan button at the rear end of a key so as to strike a string. Accordingly, the construction is bulky. For this reason, a keyboard having this type of construction cannot be incorporated into an electronic musical instrument which is required to be compact.
A keyboard device having a construction as shown in Japanese Utility Model No. 10810/1974, has been used.
The key used in this keyboard device is molded with a synthetic resin and moved in a see-saw fashion about a fulcrum at the rear end of the key by a return spring.
More particularly, at the initial stage of the key depression, that is at an instant when a finger of the performer comes into contact with a key to rotate it against the force of a return spring, the heavy key is quickly moved from the stable state. Moreover, since the key has a substantially large inertia due to its weight it is necessary to provide a large force to initiate the key depression and, consequently a large reaction is applied to the finger when it is brought into contact with the key, thus causing fatigue in the fingers of the performer.
Once the key depression has started, the key, due to its inertia, moves ahead of the movement of the finger with the result that the reaction disappears, thus decreasing the touch sensation. Although this tendency can be prevented by increasing the stiffness of the return spring, this measure increases the reaction against the performer's fingers as the key is depressed, thereby decreasing the quality of the music performed.
When the key reaches a lower stop member, its speed is abruptly reduced to zero, again causing a large reaction.